- Preface
- New and Changed Information
- Overview
- Configuring Ethernet Interfaces
- Configuring VLANs
- Configuring Private VLANs
- Configuring Access and Trunk Interfaces
- Configuring Port Channels
- Configuring Virtual Port Channels
- Configuring Rapid PVST+
- Configuring Multiple Spanning Tree
- Configuring STP Extensions
- Configuring MAC Address Tables
- Configuring IGMP Snooping
- Configuring Traffic Storm Control
- Index
- Information About vPCs
- Guidelines and Limitations for vPCs
- Configuring vPCs
- Configuring the vPC Peer Switch
- Verifying the vPC Configuration
- vPC Default Settings
Configuring Virtual Port Channels
This chapter contains the following sections:
- Information About vPCs
- Guidelines and Limitations for vPCs
- Configuring vPCs
- Configuring the vPC Peer Switch
- Verifying the vPC Configuration
- vPC Default Settings
Information About vPCs
vPC Overview
A virtual port channel (vPC) allows links that are physically connected to two different Cisco Nexus devices or Cisco Nexus Fabric Extenders to appear as a single port channel by a third device (see the following figure). The third device can be a switch, server, or any other networking device. You can configure vPCs in topologies that include Cisco Nexus devices connected to Cisco Nexus Fabric Extenders. A vPC can provide multipathing, which allows you to create redundancy by enabling multiple parallel paths between nodes and load balancing traffic where alternative paths exist.
You configure the EtherChannels by using one of the following:
When you configure the EtherChannels in a vPC—including the vPC peer link channel—each switch can have up to 16 active links in a single EtherChannel.
Note | You must enable the vPC feature before you can configure or run the vPC functionality. |
To enable the vPC functionality, you must create a peer-keepalive link and a peer-link under the vPC domain for the two vPC peer switches to provide the vPC functionality.
To create a vPC peer link you configure an EtherChannel on one Cisco Nexus device by using two or more Ethernet ports. On the other switch, you configure another EtherChannel again using two or more Ethernet ports. Connecting these two EtherChannels together creates a vPC peer link.
Note | We recommend that you configure the vPC peer-link EtherChannels as trunks. |
The vPC domain includes both vPC peer devices, the vPC peer-keepalive link, the vPC peer link, and all of the EtherChannels in the vPC domain connected to the downstream device. You can have only one vPC domain ID on each vPC peer device.
Note | Always attach all vPC devices using EtherChannels to both vPC peer devices. |
A vPC provides the following benefits:
- Allows a single device to use an EtherChannel across two upstream devices
- Eliminates Spanning Tree Protocol (STP) blocked ports
- Provides a loop-free topology
- Uses all available uplink bandwidth
- Provides fast convergence if either the link or a switch fails
- Provides link-level resiliency
- Assures high availability
Terminology
vPC Terminology
The terminology used in vPCs is as follows:
-
vPC—combined EtherChannel between the vPC peer devices and the downstream device.
-
vPC peer device—One of a pair of devices that are connected with the special EtherChannel known as the vPC peer link.
-
vPC peer link—link used to synchronize states between the vPC peer devices.
-
vPC member port—Interfaces that belong to the vPCs.
-
vPC domain—domain that includes both vPC peer devices, the vPC peer-keepalive link, and all of the port channels in the vPC connected to the downstream devices. It is also associated to the configuration mode that you must use to assign vPC global parameters. The vPC domain ID must be the same on both switches.
-
vPC peer-keepalive link—The peer-keepalive link monitors the vitality of a vPC peer Cisco Nexus device. The peer-keepalive link sends configurable, periodic keepalive messages between vPC peer devices.
No data or synchronization traffic moves over the vPC peer-keepalive link; the only traffic on this link is a message that indicates that the originating switch is operating and running vPCs.
Supported vPC Topologies
Cisco Nexus Device vPC Topology
vPC Domain
To create a vPC domain, you must first create a vPC domain ID on each vPC peer switch using a number from 1 to 1000. This ID must be the same on a set of vPC peer devices.
You can configure the EtherChannels and vPC peer links by using LACP or no protocol. When possible, we recommend that you use LACP on the peer-link, because LACP provides configuration checks against a configuration mismatch on the EtherChannel.
The vPC peer switches use the vPC domain ID that you configure to automatically assign a unique vPC system MAC address. Each vPC domain has a unique MAC address that is used as a unique identifier for the specific vPC-related operations, although the switches use the vPC system MAC addresses only for link-scope operations, such as LACP. We recommend that you create each vPC domain within the contiguous network with a unique domain ID. You can also configure a specific MAC address for the vPC domain, rather than having the Cisco NX-OS software assign the address.
The vPC peer switches use the vPC domain ID that you configure to automatically assign a unique vPC system MAC address. The switches use the vPC system MAC addresses only for link-scope operations, such as LACP or BPDUs. You can also configure a specific MAC address for the vPC domain.
We recommend that you configure the same VPC domain ID on both peers and, the domain ID should be unique in the network. For example, if there are two different VPCs (one in access and one in aggregation) then each vPC should have a unique domain ID.
After you create a vPC domain, the Cisco NX-OS software automatically creates a system priority for the vPC domain. You can also manually configure a specific system priority for the vPC domain.
Note | If you manually configure the system priority, you must ensure that you assign the same priority value on both vPC peer switches. If the vPC peer switches have different system priority values, the vPC will not come up. |
Peer-Keepalive Link and Messages
The Cisco NX-OS software uses a peer-keepalive link between the vPC peers to transmit periodic, configurable keepalive messages. You must have Layer 3 connectivity between the peer switches to transmit these messages; the system cannot bring up the vPC peer link unless a peer-keepalive link is already up and running.
You can configure a hold-timeout and a timeout value simultaneously.
Hold-timeout value—The hold-timeout value range is between 3 to 10 seconds, with a default value of 3 seconds. This timer starts when the vPC peer link goes down. The purpose of the hold-timeout period is to prevent false-positive cases.
If you configure a hold-timeout value that is lower than the timeout value, then the vPC system ignores vPC peer-keepalive messages for the hold-timeout period and considers messages for the reminder of the timeout period. If no keepalive message is received for this period, the vPC secondary device takes over the role of the primary device. For example, if the hold-timeout value is 3 seconds and the timeout value is 5 seconds, for the first 3 seconds vPC keepalive messages are ignored (such as, when accommodating a supervisor failure for a few seconds after peer link failure) and keepalive messages are considered for the remaining timeout period of 2 seconds. After this period, the vPC secondary device takes over as the primary device, in case there is no keep alive message.
Timeout value—The timeout value range is between 3 to 20 seconds, with a default value of 5 seconds. This timer starts at the end of the hold-timeout interval. If you configure a timeout value that is lower than or equal to the hold-timeout value, then the timeout duration is initiated after the hold-timeout period. For example, if the timeout value is 3 seconds and the hold-timeout value is 5 seconds, the timeout period starts after 5 seconds.
Note | We recommend that you configure the vPC peer-keepalive link on the Cisco Nexus device to run in the management VRF using the mgmt 0 interfaces. If you configure the default VRF, ensure that the vPC peer link is not used to carry the vPC peer-keepalive messages. |
Compatibility Parameters for vPC Peer Links
Many configuration and operational parameters must be identical on all interfaces in the vPC. After you enable the vPC feature and configure the peer link on both vPC peer switches, Cisco Fabric Services (CFS) messages provide a copy of the configuration on the local vPC peer switch configuration to the remote vPC peer switch. The system then determines whether any of the crucial configuration parameters differ on the two switches.
Enter the show vpc consistency-parameters command to display the configured values on all interfaces in the vPC. The displayed configurations are only those configurations that would limit the vPC peer link and vPC from coming up.
The compatibility check process for vPCs differs from the compatibility check for regular EtherChannels.
Configuration Parameters That Must Be Identical
The configuration parameters in this section must be configured identically on both switches at either end of the vPC peer link.
Note | You must ensure that all interfaces in the vPC have the identical operational and configuration parameters listed in this section. Enter the show vpc consistency-parameters command to display the configured values on all interfaces in the vPC. The displayed configurations are only those configurations that would limit the vPC peer link and vPC from coming up. |
The switch automatically checks for compatibility of these parameters on the vPC interfaces. The per-interface parameters must be consistent per interface, and the global parameters must be consistent globally.
- Port-channel mode: on, off, or active
- Link speed per channel
- Duplex mode per channel
- Trunk mode per channel:
- Spanning Tree Protocol (STP) mode
- STP region configuration for Multiple Spanning Tree (MST)
- Enable or disable state per VLAN
- STP global settings:
- STP interface settings:
If any of these parameters are not enabled or defined on either switch, the vPC consistency check ignores those parameters.
Note | To ensure that none of the vPC interfaces are in the suspend mode, enter the show vpc brief and show vpc consistency-parameters commands and check the syslog messages. |
Configuration Parameters That Should Be Identical
When any of the following parameters are not configured identically on both vPC peer switches, a misconfiguration might cause undesirable behavior in the traffic flow:
- MAC aging timers
- Static MAC entries
- VLAN interface—Each switch on the end of the vPC peer link must have a VLAN interface configured for the same VLAN on both ends and they must be in the same administrative and operational mode. Those VLANs configured on only one switch of the peer link do not pass traffic using the vPC or peer link. You must create all VLANs on both the primary and secondary vPC switches, or the VLAN will be suspended.
- Private VLAN configuration
- All ACL configurations and parameters
- Quality of service (QoS) configuration and parameters—Local parameters; global parameters must be identical
- STP interface settings:
To ensure that all the configuration parameters are compatible, we recommend that you display the configurations for each vPC peer switch once you configure the vPC.
vPC Peer Links
A vPC peer link is the link that is used to synchronize the states between the vPC peer devices.
Note | You must configure the peer-keepalive link before you configure the vPC peer link or the peer link will not come up. |
vPC Peer Link Overview
You can have only two switches as vPC peers; each switch can serve as a vPC peer to only one other vPC peer. The vPC peer switches can also have non-vPC links to other switches.
To make a valid configuration, you configure an EtherChannel on each switch and then configure the vPC domain. You assign the EtherChannel on each switch as a peer link. For redundancy, we recommend that you should configure at least two dedicated ports into the EtherChannel; if one of the interfaces in the vPC peer link fails, the switch automatically falls back to use another interface in the peer link.
Note | We recommend that you configure the EtherChannels in trunk mode. |
Many operational parameters and configuration parameters must be the same in each switch connected by a vPC peer link. Because each switch is completely independent on the management plane, you must ensure that the switches are compatible on the critical parameters. vPC peer switches have separate control planes. After configuring the vPC peer link, you should display the configuration on each vPC peer switch to ensure that the configurations are compatible.
Note | You must ensure that the two switches connected by the vPC peer link have certain identical operational and configuration parameters. |
When you configure the vPC peer link, the vPC peer switches negotiate that one of the connected switches is the primary switch and the other connected switch is the secondary switch. By default, the Cisco NX-OS software uses the lowest MAC address to elect the primary switch. The software takes different actions on each switch—that is, the primary and secondary—only in certain failover conditions. If the primary switch fails, the secondary switch becomes the operational primary switch when the system recovers, and the previously primary switch is now the secondary switch.
You can also configure which of the vPC switches is the primary switch. If you want to configure the role priority again to make one vPC switch the primary switch, configure the role priority on both the primary and secondary vPC switches with the appropriate values, shut down the EtherChannel that is the vPC peer link on both switches by entering the shutdown command, and reenable the EtherChannel on both switches by entering the no shutdown command.
MAC addresses that are learned over vPC links are also synchronized between the peers.
Configuration information flows across the vPC peer links using the Cisco Fabric Services over Ethernet (CFSoE) protocol. All MAC addresses for those VLANs configured on both switches are synchronized between vPC peer switches. The software uses CFSoE for this synchronization.
If the vPC peer link fails, the software checks the status of the remote vPC peer switch using the peer-keepalive link, which is a link between vPC peer switches, to ensure that both switches are up. If the vPC peer switch is up, the secondary vPC switch disables all vPC ports on its switch. The data then forwards down the remaining active links of the EtherChannel.
The software learns of a vPC peer switch failure when the keepalive messages are not returned over the peer-keepalive link.
Use a separate link (vPC peer-keepalive link) to send configurable keepalive messages between the vPC peer switches. The keepalive messages on the vPC peer-keepalive link determines whether a failure is on the vPC peer link only or on the vPC peer switch. The keepalive messages are used only when all the links in the peer link fail.
vPC Number
Once you have created the vPC domain ID and the vPC peer link, you can create EtherChannels to attach the downstream switch to each vPC peer switch. That is, you create one single EtherChannel on the downstream switch with half of the ports to the primary vPC peer switch and the other half of the ports to the secondary peer switch.
On each vPC peer switch, you assign the same vPC number to the EtherChannel that connects to the downstream switch. You will experience minimal traffic disruption when you are creating vPCs. To simplify the configuration, you can assign the vPC ID number for each EtherChannel to be the same as the EtherChannel itself (that is, vPC ID 10 for EtherChannel 10).
Note | The vPC number that you assign to the EtherChannel that connects to the downstream switch from the vPC peer switch must be identical on both vPC peer switches. |
vPC Interactions with Other Features
Configuring vPC Peer Links and Links to the Core
Configure the command line interface by using a track object and a track list that is associated with the Layer 3 link to the core and on all vPC peer links on both vPC peer devices. You use this configuration to avoid dropping traffic if that particular module goes down because when all the tracked objects on the track list go down, the system does the following:
Stops the vPC primary peer device sending peer-keepalive messages which forces the vPC secondary peer device to take over.
Brings down all the downstream vPCs on that vPC peer device, which forces all the traffic to be rerouted in the access switch toward the other vPC peer device.
Once you configure this feature and if the module fails, the system automatically suspends all the vPC links on the primary vPC peer device and stops the peer-keepalive messages. This action forces the vPC secondary device to take over the primary role and all the vPC traffic to go to this new vPC primary device until the system stabilizes.
Create a track list that contains all the links to the core and all the vPC peer links as its object. Enable tracking for the specified vPC domain for this track list. Apply this same configuration to the other vPC peer device.
To configure a track list to switch over vPC to the remote peer when all related interfaces fail:
1. switch# configure terminal
2. switch(config)# interface type slot/port
3. switch(config-if)# track track-id interface type slot/port line-protocol
4. switch(config-track)# track track-id interface type slot/port line-protocol
5. switch(config)# track track-id interface port-channel port line-protocol
6. switch(config)# track track-id list boolean [OR | AND]
7. switch(config-track)# object number
8. switch(config-track)# end
9. switch(config)# vpc domain domain-id
10. switch(config-vpc-domain)# track number
11. (Optional) switch(config)# show vpc brief
12. (Optional) switch(config)# copy running-config startup-config
DETAILED STEPS
This example shows how to configure a track list to trigger when all the objects fail using Boolean OR:
switch# configure terminal switch(config)# interface ethernet 8/35 switch(config-if)# track 35 interface ethernet 8/35 line-protocol switch(config-track)# track 23 interface ethernet 8/33 line-protocol switch(config)# track 55 interface port-channel 100 line-protocol switch(config)# track 44 list boolean OR switch(config-track)# object 23 switch(config-track)# object 35 switch(config-track)# object 55 switch(config-track)# end switch(config)# vpc domain 1 switch(config-vpc-domain)# track 44 switch(config)# copy running-config startup-config
vPC and LACP
The Link Aggregation Control Protocol (LACP) uses the system MAC address of the vPC domain to form the LACP Aggregation Group (LAG) ID for the vPC.
You can use LACP on all the vPC EtherChannels, including those channels from the downstream switch. We recommend that you configure LACP with active mode on the interfaces on each EtherChannel on the vPC peer switches. This configuration allows you to more easily detect compatibility between switches, unidirectional links, and multihop connections, and provides dynamic reaction to run-time changes and link failures.
The vPC peer link supports 16 EtherChannel interfaces.
Note | When you manually configure the system priority, you must ensure that you assign the same priority value on both vPC peer switches. If the vPC peer switches have different system priority values, vPC does not come up. |
vPC Peer Links and STP
When you first bring up the vPC functionality, STP reconverges. STP treats the vPC peer link as a special link and always includes the vPC peer link in the STP active topology.
We recommend that you set all the vPC peer link interfaces to the STP network port type so that Bridge Assurance is automatically enabled on all vPC peer links. We also recommend that you do not enable any of the STP enhancement features on VPC peer links.
You must configure a list of parameters to be identical on the vPC peer switches on both sides of the vPC peer link.
STP is distributed; that is, the protocol continues running on both vPC peer switches. However, the configuration on the vPC peer switch elected as the primary switch controls the STP process for the vPC interfaces on the secondary vPC peer switch.
The primary vPC switch synchronizes the STP state on the vPC secondary peer switch using Cisco Fabric Services over Ethernet (CFSoE).
The vPC manager performs a proposal/handshake agreement between the vPC peer switches that sets the primary and secondary switches and coordinates the two switches for STP. The primary vPC peer switch then controls the STP protocol for vPC interfaces on both the primary and secondary switches.
The Bridge Protocol Data Units (BPDUs) use the MAC address set for the vPC for the STP bridge ID in the designated bridge ID field. The vPC primary switch sends these BPDUs on the vPC interfaces.
Note | Display the configuration on both sides of the vPC peer link to ensure that the settings are identical. Use the show spanning-tree command to display information about the vPC. |
vPC and ARP
Table synchronization across vPC peers is managed in Cisco NX-OS using the reliable transport mechanism of the Cisco Fabric Services over Ethernet (CFSoE) protocol. To support faster convergence of address tables between the vPC peers, the ip arp synchronize command must be enabled. This convergence is designed to overcome the delay involved in ARP table restoration when the peer-link port channel flaps or when a vPC peer comes back online.
To improve performance, we recommend that you turn on the ARP sync feature. By default, it is not enabled.
To check whether or not ARP sync is enabled, enter the following command:
switch# show running
To enable ARP sync, enter the following command:
switch(config-vpc-domain) # ip arp synchronize
CFSoE
The Cisco Fabric Services over Ethernet (CFSoE) is a reliable state transport mechanism that you can use to synchronize the actions of the vPC peer devices. CFSoE carries messages and packets for many features linked with vPC, such as STP and IGMP. Information is carried in CFS/CFSoE protocol data units (PDUs).
When you enable the vPC feature, the device automatically enables CFSoE, and you do not have to configure anything. CFSoE distributions for vPCs do not need the capabilities to distribute over IP or the CFS regions. You do not need to configure anything for the CFSoE feature to work correctly on vPCs.
You can use the show mac address-table command to display the MAC addresses that CFSoE synchronizes for the vPC peer link.
Note | Do not enter the no cfs eth distribute or the no cfs distribute command. CFSoE must be enabled for vPC functionality. If you do enter either of these commands when vPC is enabled, the system displays an error message. |
When you enter the show cfs application command, the output displays "Physical-eth," which shows the applications that are using CFSoE.
vPC Peer Switch
The vPC peer switch feature addresses performance concerns around STP convergence. This feature allows a pair of Cisco Nexus devices to appear as a single STP root in the Layer 2 topology. This feature eliminates the need to pin the STP root to the vPC primary switch and improves vPC convergence if the vPC primary switch fails.
To avoid loops, the vPC peer link is excluded from the STP computation. In vPC peer switch mode, STP BPDUs are sent from both vPC peer devices to avoid issues related to STP BPDU timeout on the downstream switches, which can cause traffic disruption.
This feature can be used with the pure peer switch topology in which the devices all belong to the vPC.
Note | Peer-switch feature is supported on networks that use vPC and STP-based redundancy is not supported. If the vPC peer-link fail in a hybrid peer-switch configuration, you can lose traffic. In this scenario, the vPC peers use the same STP root ID as well same bridge ID. The access switch traffic is split in two with half going to the first vPC peer and the other half to the second vPC peer. With the peer link failed, there is no impact on north/south traffic but east-west traffic will be lost (black-holed). |
For information on STP enhancement features and Rapid PVST+, see the Layer 2 Switching Configuration Guide for your device.
Guidelines and Limitations for vPCs
vPC has the following configuration guidelines and limitations:
-
You must enable the vPC feature before you can configure vPC peer-link and vPC interfaces.
-
You must configure the peer-keepalive link before the system can form the vPC peer link.
-
The vPC peer-link needs to be formed using a minimum of two 10-Gigabit Ethernet interfaces.
-
Only port channels can be in vPCs. A vPC can be configured on a normal port channel (switch-to-switch vPC topology) and on a port channel host interface (host interface vPC topology).
-
You must configure both vPC peer switches; the configuration is not automatically synchronized between the vPC peer devices.
-
Check that the necessary configuration parameters are compatible on both sides of the vPC peer link.
-
You may experience minimal traffic disruption while configuring vPCs.
-
When the peer-switch command is configured and vPC keepalive messages exchanged through an SVI instead of a management interface, additional Spanning Tree Protocol (STP) configuration is required. STP needs to be disabled on the dedicated link that carries the keepalive traffic between the vPC peers. You can disable STP on the dedicated link by configuring STP BPDUfilter on the both ends of the dedicated link. We recommend that the VLAN of the vPC keepalive SVI be allowed on only the interconnecting dedicated link and disallowed on all other links, including the peer link.
-
You cannot have a link for non-vPC traffic in parallel with a vPC topology. This can cause errors with the traffic forwarding logic resulting in duplicate or missed packets.
-
You cannot configure non-vPC interfaces across host ports on two different FEXs.
Configuring vPCs
Enabling vPCs
You must enable the vPC feature before you can configure and use vPCs.
1.
switch#
configure terminal
2.
switch(config)#
feature vpc
3.
(Optional)
switch#
show feature
4.
(Optional)
switch#
copy running-config startup-config
DETAILED STEPS
This example shows how to enable the vPC feature:
switch# configure terminal switch(config)# feature vpc
Disabling vPCs
You can disable the vPC feature.
Note | When you disable the vPC feature, the Cisco Nexus device clears all the vPC configurations. |
1.
switch#
configure terminal
2.
switch(config)#
no feature vpc
3.
(Optional)
switch#
show feature
4.
(Optional)
switch#
copy running-config startup-config
DETAILED STEPS
This example shows how to disable the vPC feature:
switch# configure terminal switch(config)# no feature vpc
Creating a vPC Domain
You must create identical vPC domain IDs on both the vPC peer devices. This domain ID is used to automatically form the vPC system MAC address.
Ensure that you have enabled the vPC feature.
You must configure both switches on either side of the vPC peer link.
1.
switch#
configure
terminal
2.
switch(config)#
vpc
domain
domain-id
3.
(Optional)
switch#
show vpc
brief
4.
(Optional)
switch#
copy
running-config startup-config
DETAILED STEPS
This example shows how to create a vPC domain:
switch# configure terminal switch(config)# vpc domain 5
Configuring a vPC Keepalive Link and Messages
You can configure the destination IP for the peer-keepalive link that carries the keepalive messages. Optionally, you can configure other parameters for the keepalive messages.
The Cisco NX-OS software uses the peer-keepalive link between the vPC peers to transmit periodic, configurable keepalive messages. You must have Layer 3 connectivity between the peer devices to transmit these messages. The system cannot bring up the vPC peer link unless the peer-keepalive link is already up and running.
Ensure that both the source and destination IP addresses used for the peer-keepalive message are unique in your network and these IP addresses are reachable from the Virtual Routing and Forwarding (VRF) instance associated with the vPC peer-keepalive link.
Note | We recommend that you configure a separate VRF instance and put a Layer 3 port from each vPC peer switch into that VRF instance for the vPC peer-keepalive link. Do not use the peer link itself to send vPC peer-keepalive messages. |
Ensure that you have enabled the vPC feature.
You must configure the vPC peer-keepalive link before the system can form the vPC peer link.
You must configure both switches on either side of the vPC peer link.
1.
switch#
configure terminal
2.
switch(config)#
vpc domain
domain-id
3.
switch(config-vpc-domain)#
peer-keepalive destination
ipaddress [hold-timeout
secs |
interval
msecs {timeout
secs} | precedence {prec-value |
network |
internet |
critical |
flash-override |
flash |
immediate priority |
routine} | tos {tos-value |
max-reliability |
max-throughput |
min-delay |
min-monetary-cost |
normal} |
tos-byte
tos-byte-value} |
source
ipaddress |
vrf {name |
management vpc-keepalive}]
4.
(Optional)
switch(config-vpc-domain)#
vpc peer-keepalive destination ipaddress source
ipaddress
5.
(Optional)
switch#
show vpc peer-keepalive
6.
(Optional)
switch#
copy running-config startup-config
DETAILED STEPS
Command or Action | Purpose | |||
---|---|---|---|---|
Step 1 |
switch#
configure terminal
|
Enters global configuration mode. | ||
Step 2 |
switch(config)#
vpc domain
domain-id
|
Creates a vPC domain on the switch if it does not already exist, and enters the vpc-domain configuration mode. | ||
Step 3 |
switch(config-vpc-domain)#
peer-keepalive destination
ipaddress [hold-timeout
secs |
interval
msecs {timeout
secs} | precedence {prec-value |
network |
internet |
critical |
flash-override |
flash |
immediate priority |
routine} | tos {tos-value |
max-reliability |
max-throughput |
min-delay |
min-monetary-cost |
normal} |
tos-byte
tos-byte-value} |
source
ipaddress |
vrf {name |
management vpc-keepalive}]
|
Configures the IPv4 address for the remote end of the vPC peer-keepalive link.
The management ports and VRF are the defaults. | ||
Step 4 |
switch(config-vpc-domain)#
vpc peer-keepalive destination ipaddress source
ipaddress
| (Optional)
Configures a separate VRF instance and puts a Layer 3 port from each vPC peer device into that VRF for the vPC peer-keepalive link. | ||
Step 5 |
switch#
show vpc peer-keepalive
| (Optional)
Displays information about the configuration for the keepalive messages. | ||
Step 6 |
switch#
copy running-config startup-config
| (Optional)
Copies the running configuration to the startup configuration. |
This example shows how to configure the destination IP address for the vPC-peer-keepalive link:
switch# configure terminal switch(config)# vpc domain 5 switch(config-vpc-domain)# peer-keepalive destination 10.10.10.42
This example shows how to set up the peer keepalive link connection between the primary and secondary vPC device:
switch(config)# vpc domain 100 switch(config-vpc-domain)# peer-keepalive destination 192.168.2.2 source 192.168.2.1 Note:--------:: Management VRF will be used as the default VRF ::-------- switch(config-vpc-domain)#
This example shows how to create a separate VRF named vpc_keepalive for the vPC keepalive link and how to verify the new VRF:
vrf context vpc_keepalive interface Ethernet1/31 switchport access vlan 123 interface Vlan123 vrf member vpc_keepalive ip address 123.1.1.2/30 no shutdown vpc domain 1 peer-keepalive destination 123.1.1.1 source 123.1.1.2 vrf vpc_keepalive L3-NEXUS-2# show vpc peer-keepalive vPC keep-alive status : peer is alive --Peer is alive for : (154477) seconds, (908) msec --Send status : Success --Last send at : 2011.01.14 19:02:50 100 ms --Sent on interface : Vlan123 --Receive status : Success --Last receive at : 2011.01.14 19:02:50 103 ms --Received on interface : Vlan123 --Last update from peer : (0) seconds, (524) msec vPC Keep-alive parameters --Destination : 123.1.1.1 --Keepalive interval : 1000 msec --Keepalive timeout : 5 seconds --Keepalive hold timeout : 3 seconds --Keepalive vrf : vpc_keepalive --Keepalive udp port : 3200 --Keepalive tos : 192 The services provided by the switch , such as ping, ssh, telnet, radius, are VRF aware. The VRF name need to be configured or specified in order for the correct routing table to be used. L3-NEXUS-2# ping 123.1.1.1 vrf vpc_keepalive PING 123.1.1.1 (123.1.1.1): 56 data bytes 64 bytes from 123.1.1.1: icmp_seq=0 ttl=254 time=3.234 ms 64 bytes from 123.1.1.1: icmp_seq=1 ttl=254 time=4.931 ms 64 bytes from 123.1.1.1: icmp_seq=2 ttl=254 time=4.965 ms 64 bytes from 123.1.1.1: icmp_seq=3 ttl=254 time=4.971 ms 64 bytes from 123.1.1.1: icmp_seq=4 ttl=254 time=4.915 ms --- 123.1.1.1 ping statistics --- 5 packets transmitted, 5 packets received, 0.00% packet loss round-trip min/avg/max = 3.234/4.603/4.971 ms
Creating a vPC Peer Link
You can create a vPC peer link by designating the EtherChannel that you want on each switch as the peer link for the specified vPC domain. We recommend that you configure the EtherChannels that you are designating as the vPC peer link in trunk mode and that you use two ports on separate modules on each vPC peer switch for redundancy.
Ensure that you have enabled the vPC feature.
You must configure both switches on either side of the vPC peer link
1.
switch#
configure terminal
2.
switch(config)#
interface port-channel
channel-number
3.
switch(config-if)#
vpc peer-link
4.
(Optional)
switch#
show vpc brief
5.
(Optional)
switch#
copy running-config startup-config
DETAILED STEPS
Command or Action | Purpose | |
---|---|---|
Step 1 |
switch#
configure terminal
|
Enters global configuration mode. |
Step 2 |
switch(config)#
interface port-channel
channel-number
|
Selects the EtherChannel that you want to use as the vPC peer link for this switch, and enters the interface configuration mode. |
Step 3 |
switch(config-if)#
vpc peer-link
|
Configures the selected EtherChannel as the vPC peer link, and enters the vpc-domain configuration mode. |
Step 4 |
switch#
show vpc brief
| (Optional)
Displays information about each vPC, including information about the vPC peer link. |
Step 5 |
switch#
copy running-config startup-config
| (Optional)
Copies the running configuration to the startup configuration. |
This example shows how to configure a vPC peer link:
switch# configure terminal switch(config)# interface port-channel 20 switch(config-if)# vpc peer-link
Checking the Configuration Compatibility
After you have configured the vPC peer link on both vPC peer switches, check that the configurations are consistent on all vPC interfaces.
Note |
In the case of a Type 2 mismatch, the vPC is not suspended. Type 1 mismatches suspend the vPC.
Command or Action |
Purpose |
---|---|
switch# show vpc consistency-parameters {global | interface port-channel channel-number} |
Displays the status of those parameters that must be consistent across all vPC interfaces. |
switch# show vpc consistency-parameters global Legend: Type 1 : vPC will be suspended in case of mismatch Name Type Local Value Peer Value ------------- ---- ---------------------- ----------------------- QoS 2 ([], [], [], [], [], ([], [], [], [], [], []) []) Network QoS (MTU) 2 (1538, 0, 0, 0, 0, 0) (1538, 0, 0, 0, 0, 0) Network Qos (Pause) 2 (F, F, F, F, F, F) (1538, 0, 0, 0, 0, 0) Input Queuing (Bandwidth) 2 (100, 0, 0, 0, 0, 0) (100, 0, 0, 0, 0, 0) Input Queuing (Absolute 2 (F, F, F, F, F, F) (100, 0, 0, 0, 0, 0) Priority) Output Queuing (Bandwidth) 2 (100, 0, 0, 0, 0, 0) (100, 0, 0, 0, 0, 0) Output Queuing (Absolute 2 (F, F, F, F, F, F) (100, 0, 0, 0, 0, 0) Priority) STP Mode 1 Rapid-PVST Rapid-PVST STP Disabled 1 None None STP MST Region Name 1 "" "" STP MST Region Revision 1 0 0 STP MST Region Instance to 1 VLAN Mapping STP Loopguard 1 Disabled Disabled STP Bridge Assurance 1 Enabled Enabled STP Port Type, Edge 1 Normal, Disabled, Normal, Disabled, BPDUFilter, Edge BPDUGuard Disabled Disabled STP MST Simulate PVST 1 Enabled Enabled Allowed VLANs - 1,624 1 Local suspended VLANs - 624 - switch#
Moving Other Port Channels into a vPC
Ensure that you have enabled the vPC feature.
You must configure both switches on either side of the vPC peer link with the following procedure.
1.
switch#
configure terminal
2.
switch(config)#
interface port-channel
channel-number
3.
switch(config-if)#
vpc
number
4.
(Optional)
switch#
show vpc brief
5.
(Optional)
switch#
copy running-config startup-config
DETAILED STEPS
Command or Action | Purpose | |||
---|---|---|---|---|
Step 1 |
switch#
configure terminal
|
Enters global configuration mode. | ||
Step 2 |
switch(config)#
interface port-channel
channel-number
|
Selects the port channel that you want to put into the vPC to connect to the downstream switch, and enters interface configuration mode.
| ||
Step 3 |
switch(config-if)#
vpc
number
|
Configures the selected port channel into the vPC to connect to the downstream switch. The range is from 1 to 4096. The vPC number that you assign to the port channel that connects to the downstream switch from the vPC peer switch must be identical on both vPC peer switches. | ||
Step 4 |
switch#
show vpc brief
| (Optional)
Displays information about each vPC. | ||
Step 5 |
switch#
copy running-config startup-config
| (Optional)
Copies the running configuration to the startup configuration. |
This example shows how to configure a port channel that will connect to the downstream device:
switch# configure terminal
switch(config)# interface port-channel 20
switch(config-if)# vpc 5
Manually Configuring a vPC Domain MAC Address
Note | Configuring the system address is an optional configuration step. |
Ensure that you have enabled the vPC feature.
You must configure both switches on either side of the vPC peer link.
1.
switch#
configure terminal
2.
switch(config)#
vpc domain
domain-id
3.
switch(config-vpc-domain)#
system-mac
mac-address
4.
(Optional)
switch#
show vpc role
5.
(Optional)
switch#
copy running-config startup-config
DETAILED STEPS
Command or Action | Purpose | |
---|---|---|
Step 1 |
switch#
configure terminal
|
Enters global configuration mode. |
Step 2 |
switch(config)#
vpc domain
domain-id
|
Selects an existing vPC domain on the switch, or creates a new vPC domain, and enters the vpc-domain configuration mode. There is no default domain-id; the range is from 1 to 1000. |
Step 3 |
switch(config-vpc-domain)#
system-mac
mac-address
|
Enters the MAC address that you want for the specified vPC domain in the following format: aaaa.bbbb.cccc. |
Step 4 |
switch#
show vpc role
| (Optional)
Displays the vPC system MAC address. |
Step 5 |
switch#
copy running-config startup-config
| (Optional)
Copies the running configuration to the startup configuration. |
This example shows how to configure a vPC domain MAC address:
switch# configure terminal
switch(config)# vpc domain 5
switch(config-if)# system-mac 23fb.4ab5.4c4e
Manually Configuring the System Priority
When you create a vPC domain, the system automatically creates a vPC system priority. However, you can also manually configure a system priority for the vPC domain.
Ensure that you have enabled the vPC feature.
You must configure both switches on either side of the vPC peer link.
1.
switch#
configure terminal
2.
switch(config)#
vpc domain
domain-id
3.
switch(config-vpc-domain)#
system-priority
priority
4.
(Optional)
switch#
show vpc brief
5.
(Optional)
switch#
copy running-config startup-config
DETAILED STEPS
Command or Action | Purpose | |
---|---|---|
Step 1 |
switch#
configure terminal
|
Enters global configuration mode. |
Step 2 |
switch(config)#
vpc domain
domain-id
|
Selects an existing vPC domain on the switch, or creates a new vPC domain, and enters the vpc-domain configuration mode. There is no default domain-id; the range is from 1 to 1000. |
Step 3 |
switch(config-vpc-domain)#
system-priority
priority
|
Enters the system priority that you want for the specified vPC domain. The range of values is from 1 to 65535. The default value is 32667. |
Step 4 |
switch#
show vpc brief
| (Optional)
Displays information about each vPC, including information about the vPC peer link. |
Step 5 |
switch#
copy running-config startup-config
| (Optional)
Copies the running configuration to the startup configuration. |
This example shows how to configure a vPC peer link:
switch# configure terminal
switch(config)# vpc domain 5
switch(config-if)# system-priority 4000
Manually Configuring a vPC Peer Switch Role
By default, the Cisco NX-OS software elects a primary and secondary vPC peer switch after you configure the vPC domain and both sides of the vPC peer link. However, you may want to elect a specific vPC peer switch as the primary switch for the vPC. Then, you would manually configure the role value for the vPC peer switch that you want as the primary switch to be lower than the other vPC peer switch.
vPC does not support role preemption. If the primary vPC peer switch fails, the secondary vPC peer switch takes over to become operationally the vPC primary switch. However, the original operational roles are not restored when the formerly primary vPC comes up again.
Ensure that you have enabled the vPC feature.
You must configure both switches on either side of the vPC peer link.
1.
switch#
configure terminal
2.
switch(config)#
vpc domain
domain-id
3.
switch(config-vpc-domain)#
role priority
priority
4.
(Optional)
switch#
show vpc brief
5.
(Optional)
switch#
copy running-config startup-config
DETAILED STEPS
Command or Action | Purpose | |
---|---|---|
Step 1 |
switch#
configure terminal
|
Enters global configuration mode. |
Step 2 |
switch(config)#
vpc domain
domain-id
|
Selects an existing vPC domain on the switch, or creates a new vPC domain, and enters the vpc-domain configuration mode. There is no default domain-id; the range is from 1 to 1000. |
Step 3 |
switch(config-vpc-domain)#
role priority
priority
|
Enters the role priority that you want for the vPC system priority. The range of values is from 1 to 65535. The default value is 32667. |
Step 4 |
switch#
show vpc brief
| (Optional)
Displays information about each vPC, including information about the vPC peer link. |
Step 5 |
switch#
copy running-config startup-config
| (Optional)
Copies the running configuration to the startup configuration. |
This example shows how to configure a vPC peer link:
switch# configure terminal
switch(config)# vpc domain 5
switch(config-if)# role priority 4000
Configuring the vPC Peer Switch
Configuring a Pure vPC Peer Switch Topology
Note | The values you apply for the spanning tree priority must be identical on both vPC peers. |
Ensure that you have enabled the vPC feature.
1. switch# configure terminal
2. switch(config)# vpc domain domain-id
3. switch(config-vpc-domain)# peer-switch
4. switch(config-vpc-domain)# spanning-tree vlan vlan-range priority value
5. switch(config-vpn-domain)# exit
6. (Optional) switch(config)# show spanning-tree summary
7. (Optional) switch(config)# copy running-config startup-config
DETAILED STEPS
Command or Action | Purpose | |||
---|---|---|---|---|
Step 1 | switch# configure terminal |
Enters global configuration mode. | ||
Step 2 | switch(config)# vpc domain domain-id | Enters the vPC domain number that you want to configure. The system enters the vpc-domain configuration mode. | ||
Step 3 | switch(config-vpc-domain)# peer-switch | Enables the vPC switch pair to appear as a single STP root in the Layer 2 topology. Use the no form of the command to disable the peer switch vPC topology. | ||
Step 4 | switch(config-vpc-domain)# spanning-tree vlan vlan-range priority value | Configures the bridge priority of the VLAN. Valid values are multiples of 4096. The default value is 32768.
| ||
Step 5 | switch(config-vpn-domain)# exit | Exits the vpc-domain configuration mode. | ||
Step 6 | switch(config)# show spanning-tree summary | (Optional) Displays a summary of the spanning tree port states including the vPC peer switch. vPC peer-switch is enabled (operational) | ||
Step 7 | switch(config)# copy running-config startup-config | (Optional)
Saves the change persistently through reboots and restarts by copying the running configuration to the startup configuration. |
This example shows how to configure a pure vPC peer switch topology:
switch# configure terminal Enter configuration commands, one per line. End with CNTL/Z. switch(config)# vpc domain 5 switch(config-vpc-domain)# peer-switch 2010 Apr 28 14:44:44 switch %STP-2-VPC_PEERSWITCH_CONFIG_ENABLED: vPC peer-switch configuration is enabled. Please make sure to configure spanning tree "bridge" priority as per recommended guidelines to make vPC peer-switch operational. switch(config-vpc-domain)# exit switch(config)# spanning-tree vlan 1 priority 8192 switch(config)# show spanning-tree summary Switch is in rapid-pvst mode Root bridge for: VLAN0001-VLAN0050, VLAN0100-VLAN0149, VLAN0200-VLAN0249 VLAN0300-VLAN0349, VLAN0400-VLAN0599, VLAN0900-VLAN0999 Port Type Default is disable Edge Port [PortFast] BPDU Guard Default is disabled Edge Port [PortFast] BPDU Filter Default is disabled Bridge Assurance is enabled Loopguard Default is disabled Pathcost method used is short vPC peer-switch is enabled (operational) Name Blocking Listening Learning Forwarding STP Active ---------------------- -------- --------- -------- ---------- ---------- VLAN0001 0 0 0 16 16 VLAN0002 0 0 0 16 16 switch(config)# copy running-config startup-config switch(config)#
Configuring a Hybrid vPC Peer Switch Topology
You can configure a hybrid vPC and non-vPC peer switch topology by using the spanning-tree pseudo-information command to change the designated bridge ID so that it meets the STP VLAN-based load-balancing criteria and then change the root bridge ID priority to a value that is better than the best bridge priority. You then enable the peer switch. For more information, see the command reference for your device.
Note | If you previously configured global spanning tree parameters and you subsequently configure spanning tree pseudo information parameters, be aware that the pseudo information parameters take precedence over the global parameters. |
Ensure that you have enabled the vPC feature.
1. switch# configure terminal
2. switch(config)# spanning-tree pseudo-information
3. switch(config-pseudo)# vlan vlan-id designated priority priority
4. switch(config-pseudo)# vlan vlan-id root priority priority
5. switch(config-pseudo)# exit
6. switch(config)# vpc domain domain-id
7. switch(config-vpc-domain)# peer-switch
8. switch(config-vpc-domain)# exit
9. (Optional) switch(config)# show spanning-tree summary
10. (Optional) switch(config)# copy running-config startup-config
DETAILED STEPS
Command or Action | Purpose | |||
---|---|---|---|---|
Step 1 | switch# configure terminal |
Enters global configuration mode. | ||
Step 2 | switch(config)# spanning-tree pseudo-information |
Configures the spanning tree pseudo information.
| ||
Step 3 | switch(config-pseudo)# vlan vlan-id designated priority priority | Configures the designated bridge priority of the VLAN. Valid values are multiples of 4096 from 0 to 61440. | ||
Step 4 | switch(config-pseudo)# vlan vlan-id root priority priority | Configures the root bridge priority of the VLAN. Valid values are multiples of 4096 from 0 to 61440.
| ||
Step 5 | switch(config-pseudo)# exit | Exists spanning tree pseudo information configuration mode. | ||
Step 6 | switch(config)# vpc domain domain-id | Enters the vPC domain number that you want to configure. The system enters the vpc-domain configuration mode. | ||
Step 7 | switch(config-vpc-domain)# peer-switch | Enables the vPC switch pair to appear as a single STP root in the Layer 2 topology. Use the no form of the command to disable the peer switch vPC topology. | ||
Step 8 | switch(config-vpc-domain)# exit | Exits the vpc-domain configuration mode. | ||
Step 9 | switch(config)# show spanning-tree summary | (Optional) Displays a summary of the spanning tree port states including the vPC peer switch. Look for the following line in the command output: vPC peer-switch is enabled (operational) | ||
Step 10 | switch(config)# copy running-config startup-config | (Optional)
Saves the change persistently through reboots and restarts by copying the running configuration to the startup configuration. |
This example shows how to configure a hybrid vPC peer switch topology:
switch# configure terminal Enter configuration commands, one per line. End with CNTL/Z. switch(config)# spanning-tree pseudo-information switch(config-pseudo)# vlan 1 designated priority 8192 switch(config-pseudo)# vlan 1 root priority 4096 switch(config-pseudo)# exit switch(config)# vpc domain 5 switch(config-vpc-domain)# peer-switch switch(config-vpc-domain)# exit switch(config)# copy running-config startup-config
Verifying the vPC Configuration
Use the following commands to display vPC configuration information:
Command |
Purpose |
||
---|---|---|---|
switch# show feature |
Displays whether vPC is enabled or not. |
||
switch# show port-channel capacity |
Displays how many EtherChannels are configured and how many are still available on the switch. |
||
switch# show running-config vpc |
Displays running configuration information for vPCs. |
||
switch# show vpc brief |
Displays brief information on the vPCs. |
||
switch# show vpc consistency-parameters |
Displays the status of those parameters that must be consistent across all vPC interfaces. |
||
switch# show vpc peer-keepalive |
Displays information on the peer-keepalive messages. |
||
switch# show vpc role |
Displays the peer status, the role of the local switch, the vPC system MAC address and system priority, and the MAC address and priority for the local vPC switch. |
||
switch# show vpc statistics |
Displays statistics on the vPCs.
|
For information about the switch output, see the Command Reference for your Cisco Nexus Series switch.
vPC Default Settings
The following table lists the default settings for vPC parameters.
Parameters |
Default |
---|---|
vPC system priority |
32667 |
vPC peer-keepalive message |
Disabled |
vPC peer-keepalive interval |
1 second |
vPC peer-keepalive timeout |
5 seconds |
vPC peer-keepalive UDP port |
3200 |